(a) Field of the Invention
The present invention relates generally to solar cells. More specifically, the present invention relates to methods of manufacturing solar cells.
(b) Description of the Related Art
A solar cell is a device that converts solar light energy into electrical energy by using a photoelectric effect.
Solar cells have recently found applications as clean energy or next-generation energy that can replace or reduce dependence on less desirable energy sources, such as fossil fuels or atomic energy.
Solar cells that use silicon as a light absorption layer may be classified into crystalline substrate (Wafer) type solar cells and thin film type (amorphous, polycrystalline) solar cells.
Other representative types of solar cells include compound thin film solar cells that use CIGS (CuInGaSe2) or CdTe, Group III-V solar cells, dye sensitive solar cells, and organic solar cells.
The basic structure of a typical solar cell employs a P type semiconductor and an N type semiconductor in a conjunction structure, similar to a diode. If light is incident in the solar cell, electrons having a (−) charge and holes that have a (+) charge caused by the removal of the electrons are generated by interaction of light with the material that constitutes the semiconductor of the solar cell, generating an current when the electrons and holes move.
This phenomenon is referred to as the photovoltaic effect. Once the electrons and holes are generated, the electrons are drawn to the n type semiconductor and the holes are drawn to the p type semiconductor. This flow of electrons/holes generates an electrical current.
In a back contact solar cell, the P type semiconductor, N type semiconductor, and any metal grids connected thereto are all disposed in the rear of the solar cell.
U.S. Pat. No. 6,998,288 discloses that the fabrication of back contact solar cells can be simplified by forming both an N+ region and P+ region via an atmospheric pressure chemical vapor deposition (APCVD) at the same time, reducing the manufacturing cost of the back contact solar cell.
However, this process also presents challenges. Since the N+ region and P+ region contact each other, a short occurs between the regions and a shunt resistance of the solar cell is increased, thus lowering the cell's efficiency.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.